using System;
using System.Collections;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;

namespace DataAccess
{

    /// <summary>
    /// A helper class used to execute queries against an Sql database
    /// </summary>
    public abstract class SqlHelper
    {

        // Read the connection strings from the configuration file
        public static readonly string ConnectionString = ConfigurationManager.ConnectionStrings["ApplicationServices"].ConnectionString;

        //public static readonly string ConnectionStringLocalTransaction = ConfigurationManager.ConnectionStrings["OraConnString1"].ConnectionString;
        //public static readonly string ConnectionStringInventoryDistributedTransaction = ConfigurationManager.ConnectionStrings["OraConnString2"].ConnectionString;
        //public static readonly string ConnectionStringOrderDistributedTransaction = ConfigurationManager.ConnectionStrings["OraConnString3"].ConnectionString;
        //public static readonly string ConnectionStringProfile = ConfigurationManager.ConnectionStrings["OraProfileConnString"].ConnectionString;
        //public static readonly string ConnectionStringMembership = ConfigurationManager.ConnectionStrings["OraMembershipConnString"].ConnectionString;

        //Create a hashtable for the parameter cached
        private static readonly Hashtable ParmCache = Hashtable.Synchronized(new Hashtable());

        /// <summary>
        /// Execute a database query which does not include a select
        /// </summary>
        /// <param name="cmdType">Command type either stored procedure or SQL</param>
        /// <param name="cmdText">Acutall SQL Command</param>
        /// <param name="commandParameters">Parameters to bind to the command</param>
        /// <returns></returns>
        public static int ExecuteNonQuery(CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            // Create a new Sql command           

            var cmd = new SqlCommand();

            //Create a connection
            using (var connection = new SqlConnection(ConnectionString))
            {

                //Prepare the command
                PrepareCommand(cmd, connection, cmdType, cmdText, commandParameters);

                //Execute the command
                int val = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /// <summary>
        /// Execute an SqlCommand (that returns no resultset) against an existing database transaction 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "PublishOrders", new SqlParameter(":prodid", 24));
        /// </remarks>
        /// <param name="trans">an existing database transaction</param>
        /// <param name="cmdText"></param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <param name="cmdType"></param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            var cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }

        /// <summary>
        /// Execute an SqlCommand (that returns no resultset) against an existing database connection 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter(":prodid", 24));
        /// </remarks>
        /// <param name="connection">an existing database connection</param>
        /// <param name="cmdType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="cmdText">the stored procedure name or PL/SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {

            var cmd = new SqlCommand();

            PrepareCommand(cmd, connection, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }

        /// <summary>
        /// Execute a select query that will return a result set
        /// </summary>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="cmdText">the stored procedure name or PL/SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns></returns>
        public static SqlDataReader ExecuteReader(CommandType commandType, string cmdText, params SqlParameter[] commandParameters)
        {
            //Create the command and connection
            var cmd = new SqlCommand();
            var conn = new SqlConnection(ConnectionString);

            try
            {
                //Prepare the command to execute
                PrepareCommand(cmd, conn, commandType, cmdText, commandParameters);

                //Execute the query, stating that the connection should close when the resulting datareader has been read
                SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                return rdr;

            }
            catch
            {

                //If an error occurs close the connection as the reader will not be used and we expect it to close the connection
                conn.Close();
                throw;
            }
        }

        /// <summary>
        /// Execute an SqlCommand that returns the first column of the first record against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter(":prodid", 24));
        /// </remarks>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or PL/SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
        public static object ExecuteScalar(CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            var cmd = new SqlCommand();

            using (var conn = new SqlConnection(ConnectionString))
            {
                PrepareCommand(cmd, conn, commandType, commandText, commandParameters);
                object val = cmd.ExecuteScalar();
                cmd.Parameters.Clear();
                return val;
            }
        }

        ///	<summary>
        ///	Execute	a SqlCommand (that returns a 1x1 resultset)	against	the	specified SqlTransaction
        ///	using the provided parameters.
        ///	</summary>
        ///	<param name="transaction">A	valid SqlTransaction</param>
        ///	<param name="commandType">The CommandType (stored procedure, text, etc.)</param>
        ///	<param name="commandText">The stored procedure name	or PL/SQL command</param>
        ///	<param name="commandParameters">An array of	SqlParamters used to execute the command</param>
        ///	<returns>An	object containing the value	in the 1x1 resultset generated by the command</returns>
        public static object ExecuteScalar(SqlTransaction transaction, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            if (transaction == null)
                throw new ArgumentNullException("transaction");
            if (transaction != null && transaction.Connection == null)
                throw new ArgumentException("The transaction was rollbacked	or commited, please	provide	an open	transaction.", "transaction");

            // Create a	command	and	prepare	it for execution
            var cmd = new SqlCommand();

            PrepareCommand(cmd, transaction.Connection, commandType, commandText, commandParameters);

            // Execute the command & return	the	results
            object retval = cmd.ExecuteScalar();

            // Detach the SqlParameters	from the command object, so	they can be	used again
            cmd.Parameters.Clear();
            return retval;
        }

        /// <summary>
        /// Execute an SqlCommand that returns the first column of the first record against an existing database connection 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  Object obj = ExecuteScalar(conn, CommandType.StoredProcedure, "PublishOrders", new SqlParameter(":prodid", 24));
        /// </remarks>
        /// <param name="connection">an existing database connection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or PL/SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
        public static object ExecuteScalar(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
        {
            var cmd = new SqlCommand();

            PrepareCommand(cmd, connection, commandType, commandText, commandParameters);
            object val = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return val;
        }

        /// <summary>
        /// Add a set of parameters to the cached
        /// </summary>
        /// <param name="cacheKey">Key value to look up the parameters</param>
        /// <param name="commandParameters">Actual parameters to cached</param>
        public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters)
        {
            ParmCache[cacheKey] = commandParameters;
        }

        /// <summary>
        /// Fetch parameters from the cache
        /// </summary>
        /// <param name="cacheKey">Key to look up the parameters</param>
        /// <returns></returns>
        public static SqlParameter[] GetCachedParameters(string cacheKey)
        {
            var cachedParms = (SqlParameter[])ParmCache[cacheKey];

            if (cachedParms == null)
                return null;

            // If the parameters are in the cache
            var clonedParms = new SqlParameter[cachedParms.Length];

            // return a copy of the parameters
            for (int i = 0, j = cachedParms.Length; i < j; i++)
                clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();

            return clonedParms;
        }

        /// <summary>
        /// Internal function to prepare a command for execution by the database
        /// </summary>
        /// <param name="cmd">Existing command object</param>
        /// <param name="conn">Database connection object</param>
        /// <param name="cmdType">Command type, e.g. stored procedure</param>
        /// <param name="cmdText">Command test</param>
        /// <param name="commandParameters">Parameters for the command</param>
        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, CommandType cmdType, string cmdText, IEnumerable<SqlParameter> commandParameters)
        {

            //Open the connection if required
            if (conn.State != ConnectionState.Open)
                conn.Open();

            //Set up the command
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            cmd.CommandType = cmdType;

            //Bind it to the transaction if it exists
            //if (trans != null)
            //    cmd.Transaction = trans;

            // Bind the parameters passed in
            if (commandParameters != null)
            {
                foreach (var parm in commandParameters)
                    cmd.Parameters.Add(parm);
            }
        }

        /// <summary>
        /// Converter to use boolean data type with Sql
        /// </summary>
        /// <param name="value">Value to convert</param>
        /// <returns></returns>
        public static string SqlBit(bool value)
        {
            return value ? "Y" : "N";
        }

        /// <summary>
        /// Converter to use boolean data type with Sql
        /// </summary>
        /// <param name="value">Value to convert</param>
        /// <returns></returns>
        public static bool SqlBool(string value)
        {
            return value.Equals("Y");
        }

        public static string GetString(IDataReader rdr, int col)
        {
            return rdr.GetValue(col).Equals(DBNull.Value) ? null : rdr.GetString(col);
        }

        public static double GetDouble(IDataReader rdr, int col)
        {
            return rdr.GetValue(col).Equals(DBNull.Value) ? 0 : Convert.ToDouble(rdr.GetDecimal(col));
        }

        public static string GetString(IDataReader rdr, string col)
        {
            return rdr[col].Equals(DBNull.Value) ? null : rdr[col].ToString();
        }

        public static int GetInt(IDataReader rdr, int col)
        {
            return rdr.GetValue(col).Equals(DBNull.Value) ? 0 : Convert.ToInt32(rdr.GetInt32(col));
        }

        public static int GetInt(IDataReader rdr, string col)
        {
            return rdr[col].Equals(DBNull.Value) ? 0 : Convert.ToInt32(rdr[col]);
        }

        public static DateTime GetDate(IDataReader rdr, int col)
        {
            var dt = new DateTime();
            return rdr.GetValue(col).Equals(DBNull.Value) ? dt : Convert.ToDateTime(rdr.GetDateTime(col));
        }

        public static DateTime GetDate(IDataReader rdr, string col)
        {
            var dt = new DateTime();
            return rdr[col].Equals(DBNull.Value) ? dt : Convert.ToDateTime(rdr[col]);
        }

        public static double GetDouble(IDataReader rdr, string col)
        {
            return rdr[col].Equals(DBNull.Value) ? 0 : Convert.ToDouble(rdr[col]);
        }
    }
}
